Conventionally, glass sheets are subjected to various surface treatments to obtain high transmittance glass sheets. As a method for obtaining a high transmittance glass sheet, formation of a low reflection film on the surface of a glass sheet so as to prevent a loss of light transmittance due to surface reflection and thus to increase the light transmittance has been proposed (see Patent Literature 1).
Patent Literature 2 has proposed formation of fine irregularities serving as a low refractive index layer on the surface of a glass sheet in addition to formation of a low reflection film (i.e., an anti-reflection film) thereon. Such a structure enhances the anti-reflection effect of the low reflection film. These fine irregularities can be formed by surface treatment of the glass sheet with a fluorinating agent (such as HF gas).